Register symbols

In this section:

This table shows the existing predefined integer register symbols:

Name	Alias	Description
`x0`	`zero`	Always zero
`x1`	`ra`	Return address
`x2`	`sp`	Stack pointer
`x3`	`gp`	Global pointer
`x4`	`tp`	Thread pointer
`x5`	`t0`	Temporary register/Alternate return address
`x6`–`x7`	`t1`–`t2`	Temporary register
`x8`	`s0`/`fp`	Saved register/Frame pointer
`x9`	`s1`	Saved register
`x10`–`x11`	`a0`–`a1`	Function argument/Return value
`x12`–`x17`	`a2`–`a7`	Function argument
`x18`–`x27`	`s2`–`s11`	Saved register
`x28`–`x31`	`t3`–`t6`	Temporary register

Table 115. Predefined integer register symbols

This table shows the floating-point register symbols that are predefined for cores with the floating-point extension:

Name	Alias	Description
`f0`–`f7`	`ft0`–`ft7`	Floating-point temporaries
`f8`–`f9`	`fs0`–`fs1`	Floating-point saved registers
`f10`	`fa0`	Floating-point arguments/return values
`f11`–`f17`	`fa1`–`fa7`	Floating-point arguments
`f18`–`f27`	`fs2`–`fs11`	Floating-point saved registers
`f28`–`f31`	`ft3`–`ft6`	Floating-point temporaries

Table 116. Predefined floating-point register symbols

Note

The size of a floating-point register is equal to the precision of the FPU.

IAR Embedded Workbench for RISC-V 3.40.x